PHPUnit 10 Migration (#1302)

* Bump PHPUnit dependencies

* Set return type of base TestCase methods

From the [PHPUnit 8 release notes][1], the `TestCase` methods below now declare a `void` return type:

- `setUpBeforeClass()`
- `setUp()`
- `assertPreConditions()`
- `assertPostConditions()`
- `tearDown()`
- `tearDownAfterClass()`
- `onNotSuccessfulTest()`

[1]: https://phpunit.de/announcements/phpunit-8.html

* Ignore PHPUnit cache folder

* Adopt PHP attributes in test classes

* Declare data providers as `static`

* Add return types to test methods

* Define test classes as `final`

* Migrate phpunit.xml to phpunit 10

* Correct phpunit attribute class name

* Rename base test class

* Restructure test folders

* Fix test image paths

* Only set rules for php files in .editorconfig

* Remove php unit flag in local test env

---------

Co-authored-by: Shift <shift@laravelshift.com>

tests/Unit/EncodedImageTest.php

@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Unit;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use Intervention\Image\EncodedImage;
+use Intervention\Image\Tests\BaseTestCase;
+
+#[CoversClass(\Intervention\Image\EncodedImage::class)]
+final class EncodedImageTest extends BaseTestCase
+{
+    public function testConstructor(): void
+    {
+        $image = new EncodedImage('foo', 'bar');
+        $this->assertInstanceOf(EncodedImage::class, $image);
+    }
+
+    public function testSave(): void
+    {
+        $image = new EncodedImage('foo', 'bar');
+        $path = __DIR__ . '/foo.tmp';
+        $this->assertFalse(file_exists($path));
+        $image->save($path);
+        $this->assertTrue(file_exists($path));
+        $this->assertEquals('foo', file_get_contents($path));
+        unlink($path);
+    }
+
+    public function testToDataUri(): void
+    {
+        $image = new EncodedImage('foo', 'bar');
+        $this->assertEquals('data:bar;base64,Zm9v', $image->toDataUri());
+    }
+
+    public function testToString(): void
+    {
+        $image = new EncodedImage('foo', 'bar');
+        $this->assertEquals('foo', (string) $image);
+    }
+
+    public function testMediaType(): void
+    {
+        $image = new EncodedImage('foo');
+        $this->assertEquals('application/octet-stream', $image->mediaType());
+
+        $image = new EncodedImage('foo', 'image/jpeg');
+        $this->assertEquals('image/jpeg', $image->mediaType());
+    }
+
+    public function testMimetype(): void
+    {
+        $image = new EncodedImage('foo');
+        $this->assertEquals('application/octet-stream', $image->mimetype());
+
+        $image = new EncodedImage('foo', 'image/jpeg');
+        $this->assertEquals('image/jpeg', $image->mimetype());
+    }
+}